The invention relates generally to roller bearings. More particularly, the invention relates to a unitized, multirow bearing assembly containing both tapered and cylindrical rollers.
Various rotatable devices such as rolling mill rolls or other shaft-like members are formed with reduced-diameter end portions, commonly referred to as roll necks, which are received in bearing assemblies that are mounted in fixed frame or housing structures commonly referred to as chocks. Because the various forces and loads on such rolls or other shaft-like devices are frequently quite substantial, the bearings for such rolls must be capable of withstanding high radial and axial loads. Consequently, the bearings for such devices have commonly included multiple rows of tapered anti-friction bearing rollers, with annular conical raceways for axially adjacent rows of such tapered rollers. Additionally, because of the dirty or corrosive conditions of many of the environments in which such bearings are employed, such bearings have frequently been provided in self-contained, unitized, cartridge-type assemblies. Examples of such unitized roller bearing assemblies are disclosed in U.S. Pat. Nos. 4,235,485; 4,336,971; 4,422,698; and 4,427,242, the disclosures of which are incorporated by reference herein.
The previous roller bearing assemblies of the type described above have frequently been constructed with multi-piece radially inner and outer race members (or race member assemblies) that require an inordinately large number of parts or associated components. Furthermore, because of the multiplicity of parts or associated components, such previous roller bearing assemblies have proved to be inordinately complex and expensive to manufacture, assemble, and maintain, as well as frequently being difficult to seal in order to prevent contamination from entering the bearing and lubricant from leaking out into work areas and onto work pieces. Many of such prior roller bearing assemblies have also required automatic lubrication systems used for piping or otherwise conveying lubricant to the bearing assembly. Such lubrication systems add to the expense, complexity, and maintenance burden for the devices or systems in which they are used.
In addition to the disadvantages discussed above, the multi-piece parts or associated components of the radially inner and radially outer race members (or race member assemblies) of the prior bearings were generally required to be very precisely machined and/or mated as matched components in order to provide and maintain the desired bearing clearance for the pairs of adjacent tapered roller bearings. Thus, the multiple pieces or components of the radially inner and radially outer race members were typically not reversible or interchangeable from one axial side end of the bearing assembly to the other, and thus had to be carefully assembled in a specific order and orientation in order to obtain the desired bearing clearance. In addition, in such multi-piece constructions with the pairs of adjacent and oppositely-facing tapered rollers, a number of axial spacer members were frequently required between axially adjacent rows of rollers in order to control the end play of the overall bearing assembly. The multiplicity of such axial spacer members, and the fact that each axial spacer was precisely machined and/or mated as a matched component for its exact axial location, further increased the chance of incorrect or reversed assembly of the various components. Furthermore, such axial spacer members frequently included openings and/or channels for conveying lubricant to the bearing assembly interior and thus were subject to being crushed or otherwise failing under high axial thrust loading conditions.
Accordingly, it is one of the general objects of the present invention to provide a fully-sealed, self-contained roller bearing assembly with a minimum number of parts and/or associated components, thereby simplifying and reducing the expense of the bearing assembly's manufacture, assembly and maintenance. Another object of the invention is to maximize the axial interchangeability and/or axial reversibility of the various parts and components in order to reduce the possibility of improper assembly or improper installation of the bearing assembly. Still another object of the present invention is to provide such a bearing assembly that is packed with lubricant during its assembly and that does not require an auxiliary lubrication system, thereby being more effectively sealed and less costly to install and maintain. In addition to the above, it is an object of the present invention to provide a bearing assembly in which the proper radial and axial bearing clearance is more easily obtained, controlled, and maintained, both during initial assembly and during service after wear has occurred.
In accordance with the present invention, a self-contained roller bearing assembly includes radially inner and radially outer bearing race members (or bearing race member assemblies) coaxially disposed for rotation relative to one another in a radially-spaced apart relationship. At least one circumferential row of cylindrical rollers is rotatably disposed radially between the radially inner and radially outer bearing race members. In one preferred embodiment, a row of such cylindrical rollers is located generally axially adjacent each of the opposite axial outer ends of the bearing assembly. At least one circumferential row of tapered (or conical) rollers is similarly disposed radially between the radially inner and radially outer bearing race members, with a pair of rows of the tapered rollers in one preferred embodiment being located axially between the rows of cylindrical rollers. Alternatively, one or more rows of the cylindrical rollers can be located axially between rows of tapered rollers, with the rows of tapered rollers then being axially located generally axially adjacent each of the opposite axial outer ends of the bearing assembly.
Each of the rows of cylindrical and tapered rollers rotatably engages both a generally non-recessed annular raceway and a generally recessed annular raceway, with the raceways being located at axial locations thereon that correspond to the axial locations of the rows of rollers. The relationship of the non-recessed raceways and the inner and outer race members (or assemblies) allows the cylindrical and tapered rollers to axially adjust themselves in order to obtain and maintain desired predetermined axial and radial bearing clearances.
At least one of the radially inner and radially outer bearing race members comprises a pair of separate race member portions that are axially separable from one another. In some of the embodiments of the invention, the race member portions are spaced axially from one another by one or more axial spacer members. The axially separable race member portions are preferably fully reversible and fully interchangeable end-to-end with one another. The associated axial spacer members, if any, are also preferably fully reversible and interchangeable end-to-end. This is because of the placement of the non-recessed raceway surfaces for the cylindrical and tapered rollers, and because the axially separable race member portions, and their associated axial spacers, if any, are preferably substantially symmetrical. Such interchangeability and reversibility does not affect the predetermined desired radial and axial bearing clearance for which the race member portions and the axial spacers were sized and machined.
In addition to the above features, the preferred roller bearing assembly according to the present invention includes end sealing members that directly engage and radially interconnect the inner and outer bearing race members generally at opposite outer ends of the bearing assembly without the need for separate axial end spacers or other associated end components or end assemblies.
Additional objects, advantages and features of the present invention will become apparent from the following description and the appended claims, taken in conjunction with the accompanying drawings.